Pyroxene-garnet equilibrium and the depth facies of eclogites

Newly derived pressure-temperature diagrams of pyroxene-garnet equilibria in eclogites, distribution and transfers of calcium at different temperatures, influence of temperature and pressure on distribution and redistribution of magnesium and iron, and other basic and empirical data pertinent to relationships between thermodynamic parameters and geological formation environments of eclogite rocks, particularly the depth factor, suggest that: a) eclogites and schists are older than their metamorphic hosts, b) formation temperatures of eclogites and glaucophane schists are lower than those of their hosts, c) formation depths of the hosts are too shallow to afford formation of eclogites and of glaucophane schists. – IGR Staff.